Are There Benefits to Low Carbohydrate High Fat (LCHF) Diets?

Low carbohydrate diets have been a fad for over 60 years in the "diet" marketplace. Low carbohydrate, coupled with high fat (LCHF), such as was/is typical of the Atkins diet, diets have shown utility in the weight loss arena and in the control of type 2 diabetes in the short term. The primary consideration of any diet is the composition. This means that foods that are natural over processed should be the top priority. In addition, careful consideration of the amount, and types, of saturated fat in the diet is equally important.

Despite the many years of popularity of diets such as the Atkins diet, the benefits of adherence, beyond 12 months, with respect to effects of these types of diets for example on weight control, glucose control, and cardiovascular benefits are uncertain.

A recent report in the journal, Nutrition Journal, presented the results from a group of 100 volunteers in Sweden who maintained adherence to a LCHF diet since 2017 and were monitored through 2019. Volunteers in this long-term study were at least 18-years-old and had been consuming a LCHF diet for at least 3 months. Potential volunteers who were taking lipid-lowering medication, were known have familial hypercholesterolemia, or were unable to travel to the study site were excluded from the study.

Low carbohydrate high fat‑diet in real life assessed by diet history interviews

Each participant in the study was assessed for weight, waist and hip circumference, smoking status, level of physical activity, current medications and any illnesses. Participant blood pressure and pulse were measured three times in a seated position. Blood samples were taken for analysis of hemoglobin, sodium, potassium, and creatinine. The participants were fitted with a SenseWear Armband Pro3 (SWA) BodyMedia Inc. for 7 days to assess total energy expenditure (TEE). Each participant underwent a diet history interviews to assess food, alcohol, and dietary supplement intake for the two week period prior to the interview date. After establishing meal patterns on weekdays and weekends, each meal and between-meal snack were discussed in detail, with questions about food choices, frequencies, and portion sizes. The amounts and type of fat used in cooking was also critically evaluated. In total, 720 specific foods, recipes and dietary supplements were created for the study participants.

Throughout the study the accuracy of dietary self-reporting by the participants was assessed and the participants divided into three groups, under-reporters, accurate reporters, and over-reporters. There were only three participants identified in the over-reporting group.

With respect to the fat intake by participants, the median intake of fat was 72% of total calories. For protein, median intake was 16.9% and for carbohydrates 8.7% Saturated fatty acids comprised 31.9% of the total energy intake. The most abundant omega-3 and omega-6 polyunsaturated fatty acids (PUFA) were alfa-linoleic acid and linoleic acid, respectively.

More than 67% of the participants had a carbohydrate intake that was lower than 10% of total energy intake, but around half of those participants were classified as non-acceptable reporters. Sixty-three participants had a reported intake of less than 50 grams of carbohydrates per day and out of these, 49 were in the accurate reporter group. The dietary carbohydrate intake in this study population was low and on levels that have been suggested to induce ketosis in most people.

The fiber intake in a typical LCHF diet, including those of the study participants, is low and is one major criticism of most LCHF diets. The reason for this criticism is that it is known that a greater intake of fiber has been shown to be associated with lower risks for cardiovascular disease, type 2 diabetes, and many forms of cancer, particularly gastrointestinal cancers. Most recommendations indicate that at least 25-35 grams of fiber/day should be included in ones diet. The participants in this study had, on average, around 50% of the recommended daily fiber intake.

The most significant finding in this long-term study was that in motivated individuals it is possible to adhere to a LCHF diet for an extended period. The limitation, for assessment of long-term heath benefits, is that there was no control group of individuals included in the study. Thus, the results are observational only in their benefit.